Laser ablatable material and its use

ABSTRACT

An epoxy based resin which exhibits good laser ablation and good adherence to a substrate such a copper is provided by adding to the resin a dye or dyes having substantial energy absorption at the emission wave lengths of lasers used to laser ablate the resin. The resin with the dye or dyes included is coated onto a substrate and cured, or laminated onto a substrate in the cured condition. The required openings are formed in the cured film by laser ablation. This allows for the use of optimum techniques to be used to form micro vias.

FIELD OF THE INVENTION

[0001] This invention relates generally to a laser ablatable materialand its use and, more particularly, to an epoxy based laser ablatablematerial and its use to form a dielectric substrate having micro viastherein

BACKGROUND INFORMATION

[0002] One typical technique for forming a dielectric layer of materialwith vias therein is to utilize an epoxy based, photoimageable materialcoated onto a substrate, such as another dielectric material or aconductive material, and form the vias or other openings therein byphotolithographic techniques. Particularly suitable materials aredescribed in U.S. Pat. No. 5,026,624 and 5,300,402, and U.S. patentapplication Ser. No. 09/212,204, filed Dec. 15,1998, all commonlyassigned, and all of which are incorporated herein by reference. Asdescribed in these patents and patent application, the photoimageablematerial is coated onto a substrate and U.V. light of the appropriatewavelength is used to expose the desired pattern on the photoimageablematerial, after which the material is developed to form the desired viasand other openings in the material.

[0003] For many applications, this is a very successful technique.However, in specific applications, certain difficulties may beencountered in using photolithographic techniques. For example, incertain applications, copper foil is laminated to a dry film of materialmade according to the teachings of either U.S. Pat. Nos. 5,665,650 or5,670,750 and results in very narrow process windows and manufacturinglimitations. In particular, to achieve optimum adhesion of the foil tothe dielectric material, a low exposure dose is required. However, toolow an exposure will induce defects upon stressing, and too high anexposure dose will result in degradation of the bond between the foiland the dielectric material. Thus, in some cases, an optimum dosage toachieve good peel strengths is not adequate for small micro viadefinition. Moreover, when exposure through artwork is required,defects, such as dust particles, scratches etc., will print through,leaving a defect in the dielectric layer. With laser ablation, photoinduced defects will not appear on the dielectric layer.

SUMMARY OF THE INVENTION

[0004] According to the present invention, an epoxy based resin whichexhibits good laser ablation and good adherence to a substrate, such ascopper, is provided by adding to the resin a dye or dyes havingsubstantial energy absorption at the emission wave lengths of lasersused to laser ablate the resin. In one embodiment, the resin is coatedonto a substrate and cured, or laminated onto a substrate. Then thecured film is laser ablated to form the desired pattern of openings. Thefilm can also be either laminated or coated and cured onto a copperfoil, and the dielectric with the copper foil thereon laminated to asubstrate, This allows for the use of optimum techniques to be used toform micro vias.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0005] According to the present invention, an improved epoxy based laserablatable material is provided. The improvement in laser ablatability isachieved by incorporating into the epoxy based composition one or moredyes which increase the energy absorption of the base composition at theemitted wave length of the laser that is used to laser ablate. As iswell known in the art, different lasers emit at different wavelengths.Some examples include excimer lasers which emit at either 308 nm or 248nm, YAG lasers which emit at 532 nm, 355 nm, or 266 nm, and CO₂ laserswhich emit at 10600 nm. Thus, a dye that has an absorbance at or nearthese wavelengths incorporated into the epoxy base will significantlyenhance the laser ablation properties of the epoxy based resin. Forexample, Rhodamine B has a maximum absorbance at 543 nm, Ethyl Violethas a maximum absorbance at 596 nm, 2′,7′dichlorofluorescein has amaximum absorbance at 512 nm, and fluorescein has a maximum absorbanceat 498 nm, all of which dyes exhibit significant absorbance at 532 nmand, thus, are useful dyes for a YAG laser emitting at 532 nm. Dyeswhich exhibit significant absorbency at the 355 nm wavelength arecarbostyril 124 (maximum absorbence 349 nm) carbostyril 165 (maximumabsorbence 360 nm) coumarin 2 (maximum absorbence at 365 nm) andcoumarin 120 (maximum absorbency 352 nm) and, thus, are useful forincorporation into epoxy based resins to be ablated by YAG lasers thatemit at 355 nm wave length. Coumarin 4 (maximum absorbency 322 nm) isuseful for lasers emitting at 308 nm and p-terphenyl (maximum absorbency276 nm) is useful for lasers emitting at 266 nm.

[0006] One or more of the energy absorbing dyes described above areadded to the epoxy based resin, preferably at about 0.01 to about 1 0part by weight per 100 parts by weight of the epoxy resin. A single dyecan be utilized, or multiple dyes can be used to increase theablatability to lasers emitting at different wavelengths.

[0007] The material may also be photoimageable by photolithographictechniques, in which case a photoinitiator, preferably triarylsulfoniumhexafluroantimonate, is included in the composition. Other usefulphotoinitiators include diphenyl iodonium salts and their derivatives. Aparticular advantage to Rhodamine B and Ethyl Violet is that when theyare used with compositions that contain photoinitiators, such astriarylsulfonium hexafluroantimonate, they do not interfere with thephotochemical and curing reactions.

[0008] Alternatively, thermally labile cationic photoinitiators thatinitiate polymerization of the epoxy functionality by exposure to lightor by exposure to temperatures above about 125° C., such as alkoxysubstituted aryl onium salts of the type disclosed in U.S. Pat. Nos.4,882,221 and 5,079,778, can be utilized. On the other hand, theaddition of anthrone or other curing agents will allow epoxyformulations to be thermally stable up to about 150° C., above whichtemperature it will polymerize. Other curing agents can be chosen tocure the film as low as 80° C. The epoxy based composition with the dyeor dyes added thereto is especially adapted for use as a dielectricmaterial to coat onto a substrate to form a circuitized I/C chip carrieror circuit board with micro vias formed therein. The material can beapplied as a solution and then dried, as disclosed in U.S. Pat. Nos.5,026,626, and 5,330,402, or it can be formed into a dry film andapplied to the substrate by laminating techniques as disclosed in U.S.patent application Ser. No. 09/212,204. Also, a solventless film can beformed and applied to a substrate, such as a copper foil, and cured.

[0009] There are several techniques for applying and further processingdielectric film on substrates. One technique for applying film is tofirst apply the film to a substrate in either dry film form or coatedfilm form and cured. Vias are then laser ablated, following which copperis plated onto the surface and into the vias and then patterned. Inanother technique, after the dielectric film has been applied orlaminated, a copper foil is laminated onto the surface of the dielectricfilm and the film cured before the vias are formed. Vias are then laserablated through both the copper foil and the dielectric film, afterwhich the vias are plated with copper and the copper foil is patterned.Alternatively, the copper can be etched at the locations where the viasare to be formed, and then the vias laser ablated. In yet anothertechnique, the dielectric film can be either laminated to a copper foil,or coated onto a copper foil. The dielectric film, with the copper foilbacking is then laminated to the substrate, cured, and processed as inthe previous example. In any event, the laser ablation technique lendsitself to forming circuitized substrates.

[0010] Solvent Containing Dielectric Film

[0011] One especially useful epoxy based polymeric dielectric has solidswhich are preferably comprised of from about 10% to 80%, preferably from20% to 40%, more preferably about 30%, of phenoxy polyol resin which isthe condensation product of epichlorohydrin and bisphenol A, having amolecular weight of from about 40,000 to 130,000, preferably about60,000 to 90,000, more preferably greater than 60,000; from about 0% to80%, preferably from about 25% to 30%, most preferably about 25%, of anepoxidized multifunctional bisphenol A formaldehyde novalac resin havinga molecular weight of from about 4,000 to 10,000, preferably about 5,000to 7,000; from 0% to 90%, preferably from about 35% to 50%, morepreferably 40% to 45%, most preferably about 45%, of a diglycidyl etherof bisphenol A, preferably brominated, having a molecular weight of fromabout 600 to 2,500, preferably about 1,000 to 1,700. A dye or dyes thatabsorb energy significantly at the emitting wavelength for the laserablation for one or more lasers is added to the epoxy base, preferablyat from about 0.01 to about 1.0 part by weight per 100 parts by weightof the resin component. If the composition is to be photoimageable, aphoto initiator is present at from about 0.1 to about 15 parts,preferably about 5 parts by weight, of the total resin weight.Preferably, the photoinitiator is a cationic photoinitiator havingsulfur moiety such as a complex triarylsulfonium hexafluoroantimonatesalt. A suitable complex triarysulfonium hexafluoroantimonate saltcationic photoinitiator formerly available as UVE 1014 from GeneralElectric Company, is now available as UVI 6974 from Union CarbideCompany. The solvent component of the dielectric film preferably iscomprised of propylene glycol monomethyl ether acetate, and 0% to lessthan about 10% propylene carbonate and 0% to less than about 50% ofmethyl ethyl ketone. The propylene carbonate is preferably the conveyorfor the preferred photoinitiator if a photoinitiator is to beincorporated in the composition.

[0012] Preferably, the phenoxy polyol resin has an epoxide value of fromabout 0.001 to about 3, more preferably from about 0.01 to about 0.3,most preferably about 0.03 equivalents per kg, a weight per epoxide offrom about 10,000 to about 60,000, more preferably from about 20,000 toabout 50,000, most preferably about 37,000 and a glass transitiontemperature of from about 80 to about 150, more preferably from about 90to about 110, most preferably about 98° C.

[0013] Preferably, the multifunctional epoxy bisphenol A formaldehydenovolac resin has an epoxide value of from about 1 to about 10, morepreferably from about 3 to about 6, most preferably about 4.7equivalents per kilogram, a weight per epoxide of from about 180 toabout 300, more preferably from about 190 to about 230, most preferablyabout 215 and a melting point of from about 60° C. to about 150° C, morepreferably from about 70° C. to about about 90° C., most preferablyabout 82° C.

[0014] Preferably, the diglycidyl ether of the bisphenol A has anepoxide value of from about 0.1 to about 5, more preferably from about 1to about 3, most preferably about 1.5 equivalents per kilogram, a weightper epoxide of from about 200 to about 1,000, more preferably from abut500 to about 750, most preferably about 675 and a melting point of fromabout 70 to about 150, more preferably from about 80 to about 110, mostpreferably about 97° C.

[0015] A suitable phenoxy polyol resin is available under the trade name“PKHC”, formerly available from Union Carbide Corporation, and now fromPhenoxy Resin Associates. A suitable octafunctional bisphenol A,formerly available under the trade name “Epirez SU-8” from High TekPolymers, is now available as “Epon SU8” from Shell Chemical Company. Asuitable tetrabromobisphenol A, formerly available under the trade name“Epirez 5183” from High Tek Polymers, is now available as “Epon 1183”from Shell Chemical Company.

[0016] If a photoinitiator is not used so that there is not thephotoimaging characteristic of the film, thermal curing agents, such asdicyanodiamide (DICY) or bisphenol or substituted bisphenols, can beadded. Catalytic agents, such as 2-methylimidazol or 2-ethyl,4-methylimidizol, can also be incorporated into the composition.

[0017] The solids of the photoimageable dielectric film optionallycomprise a particulate rheology modifier, preferably a thixotropicparticulate rheology modifier. Preferably, the particulate rheologymodifier has an average particle size of from about 0.001 to about 10microns, more preferably from about 0.01 to about 5 microns. Examples ofparticulate rheology modifiers are barium sulfate, talc, aluminum oxide,antimony oxide, kaolin, finely divided silicon dioxide which may becolloidal or rendered hydrophobic, micronised talcum, micronised mica,kaolin, aluminum oxide, aluminum hydroxide, calcium silicate, aluminumsilicate, magnesium carbonate, calcium carbonate, zirconium silicate,porcelain powder, glass powder, antimony trioxide, titanium dioxide,barium titanate and barium sulfate or mixtures thereof.

[0018] Preferably, the particulate rheology modifier is silica; asuitable silica is available under the trade name Aerosil A380 silicafrom Degussa. Where the particulate rheology modifier is a thixotropicparticulate rheology modifier, it is preferred that no more than 30% beused.

[0019] Optionally, a surfactant, such as for example a nonionicsurfactant, is employed. Preferably, the surfactant is a fluorinatedpolyether; a suitable surfactant is available under the trade nameFC-430 from 3M Company.

[0020] In other embodiments, solventless epoxy systems are used. Apreferred solventless system is disclosed in commonly assigned U.S.patent application Ser. No. 09/212,204, filed Dec. 15, 1998, which isincorporated herein by reference. Again, a photoinitiator may be used ifphotoimaging is required, but can be omitted if photoimaging is notrequired.

[0021] The Solventless Dielectric Film

[0022] The solventless dielectric film is a high resolution dielectricmaterial. Preferably, the dielectric constant of the dielectric film isless than about 5, more preferably less than about 4. The dielectricfilm is thermally stable up to about 340° C. The dielectric filmpreferably is comprised of about 95% or more solids. The epoxy resinsystem comprises from about 10% to 80% of phenoxy polyol resin which isthe condensation product of epichlorohydrin and bisphenol A, having amolecular weight of from about 40,000 to about 130,000; from about 0% toabout 80% of an epoxidized multifunctional bisphenol A formaldehydenovolac resin, having a molecular weight of from about 4,000 to about10,000; from 10% to 50% of a diglycidyl ether of bisphenol A, having amolecular weight of from about 600 to 2,500; from about 10% to about 35% liquid epoxy resin, having a molecular weight of from about 200 toabout 600, preferably from about 250 to about 450. The “liquid epoxyresins” are liquid at 20° C. Preferably, the liquid epoxy resins areselected from the group consisting of a cycloaliphatic epoxy resin, abisphenol A epoxy resin, and mixtures thereof.

[0023] In one embodiment of the solventless film, the solids comprise anepoxy resin system which is preferably comprised of from about 10% toabout 80%, preferably from 10% to about 40%, more preferably from about15% to about 30% of the phenoxy polyol resin, which is the condensationproduct of epichlorohydrin and bisphenol A, having a molecular weight offrom about 40,000 to about 130,000, preferably about 60,000 to about90,000, more preferably greater than 60,000; from 0% to about 80%, morepreferably from about 12% to about 30%, most preferably from about 15%to about 20%, of an epoxidized multifunctional bisphenol A formaldehydenovolac resin, having a molecular weight of from about 4,000 to about10,000, preferably about 5,000 to about 7,000; from about 10% to about50%, preferably from about 25% to about 40%, more preferably about 27%to about 35% of a diglycidyl ether of bisphenol A, having a molecularweight of from about 600 to about 2,500, preferably about 1,000 to about1,700; from about 10% to about 35%, preferably from about 13% to about32%, more preferably from about 20% to about 30%, liquid epoxy resin. Ifthe film is to be photoimageable, from about 0 1 to about 15 parts,preferably about 5 parts by weight to 100 parts by weight of the totalresin weight, of a cationic photoinitiator is added. The solidsoptionally comprise a particulate rheology modifier from 0 to about 30%,preferably from 0.25% to about 30%, preferably from about 0.3% to about5%, most preferably from about 0.5% to about 4%.

[0024] In another embodiment of the solventless film, the solidscomprise an epoxy resin system which is preferably comprised of fromabout 5% to about 80%, preferably from 10% to about 40%, more preferablyfrom about 15% to about 30% of the phenoxy polyol resin; 0% of theepoxidized multifunctional bisphenol A formaldehyde novolac resin; fromabout 20% to about 80%, preferably from about 30% to about 70%, morepreferably about 40% to about 60% of the diglycidyl ether of bisphenolA; from about 10% to about 35%, preferably from about 13% to about 32%,more preferably about 20% to about 30%, liquid epoxy resin. If the filmis to be photoimageable from about 0.1 to about 15 parts, preferablyabout 5 parts by weight, of the total resin weight, a cationicphotoinitiator is added. The solids optionally comprise a particulaterheology modifier from 0% to about 30%, preferably from 0.25% to about30%, preferably from about 0.3% to about 5%, most preferably from about0.5% to about 4%.

[0025] The diglycidyl ether of bisphenol A is preferably halogenated,more preferably bromonated. The solvent component left over afterprocessing of the photoimageable dielectric film preferably is comprisedof propylene glycol monomethyl ether acetate, 0% to less than about 10%of the solvent, propylene carbonate, 0% to less than about 50% methylethyl ketone. The propylene carbonate is preferably the carrier for thepreferred photoinitiator.

[0026] Preferably, the phenoxy polyol resin has an epoxy value of fromabout 0.001 to about 3, more preferably from about 0.01 to about 0.3,most preferably about 0.03 equivalents per kg, a weight per epoxide offrom about 10,000 to about 60,000, more preferably from about 20,000 toabout 50,000, most preferably about 37,000 and a glass transitiontemperature of from about 80° to about 150° more preferably from about90° to about 110°, most preferably about 98° C.

[0027] Preferably, the multifunctional epoxy bisphenol A formaldehydenovolac resin has an epoxy value of from about 1 to about 10, morepreferably from about 3 to about 6, most preferably about 4.7equivalents per kilogram, a weight per epoxide of from about 180 toabout 300, more preferably from about 190 to about 230, most preferablyabout 215 and a melting point of from about 60° C. to about 150° C.,more preferably from about 70° C. to about 90° C., most preferably about82° C.

[0028] Preferably, the diglycidyl ether of the bisphenol A has an epoxyvalue of from about 0.1 to about 5, more preferably from about 1 toabout 3, most preferably about 1.5. equivalents per kilogram, a weightper epoxide of from about 200 to about 1000, more preferably from about500 to about 750, most preferably about 675 and a melting point of fromabout 70° C. to about 150° C., more preferably from about 80° C. toabout 110° C., most preferably about 97° C.

[0029] The liquid epoxy resin has a weight average molecular weight offrom about 200 to about 500, preferably from about 250 to about 450.Preferably, the liquid epoxy resin is either a bisphenol A epoxy resinor cycloaliphatic epoxy resin. The bisphenol A epoxy resin is a reactionproduct of bisphenol A and epichlorohydrin, and has an epoxy value offrom about 10 to about 4, more preferably from about 7 to about 5, mostpreferably about 5.5 equivalents per kilogram, a weight per epoxide offrom about 100 to about 250, more preferably from about 150 to about200, most preferably about 180, a weight average molecular weight offrom about 200 to about 500, preferably from about 250 to about 450,more preferably from about 300 to about 400, and a melting point ofbelow about 20° C. A suitable bisphenol A epoxy resin is a difunctionalbisphenol A epoxy resin available under the tradename Epon 826. The Epon826 resin from Shell Oil Corporation has an epoxide equivalent weight offrom about 178 to about 186 and a density of 1.6 grams/cm².

[0030] Preferably, the cycloaliphatic epoxy resin has an epoxy value offrom about 10 to about 5, more preferably from about 8 to about 6, mostpreferably about 7.3 equivalents per kilogram, a weight per epoxide offrom about 100 to about 200, more preferably from about 120 to about150, most preferably about 137, a weight average molecular weight offrom about 200 to about 500, preferably from about 250 to about 450, andpreferably a melting point of below about 20° C. Preferably, thecycloaliphatic epoxy resin is a cycloaliphatic difunctional epoxy resin,more preferably cycloaliphatic epoxy resin is 3, 4-epoxycyclohexylmethyl3,4-epoxycyclohexane-carboxylate. A suitable 3,4-epoxycyclohexylmethyl3,4-epoxy-cyclohexane-carboxylate resin is sold by Union Carbide underthe trademark “ERL-4221.” This resin has an epoxy equivalent weight offrom 131 to about 143, a freezing point of less than −20° C., a specificgravity of 1.18, and an approximate average molecular weight of fromabout 262 to about 286.

[0031] Other suitable liquid epoxy resins are vinyl cyclohexene dioxide,available under the. trade name “ERL-4206” from Union Carbide,2-(3,4-epoxycyclohexyl-5,5-spiro-3, 4epoxy) cyclohexane-meta-dioxane,available under the trade name “ERL-4234” from Union Carbide, Bis(3,4-epoxy cyclohexyl) adipate, available under the trade name “ERL4299”. ERL4299 has a freezing point of approximately 9° C., a specificgravity of 1.15 and an epoxy equivalent weight of from about 190 toabout 210 and an average approximate molecular weight of from about 380to 420; ERL-4206 has a freezing point of −5 5° C., a specific gravity of1.09, an epoxy equivalent weight of from about 70 to about 74 and anaverage approximate molecular weight of from about 140 to 148; ERL4234has a melting point of approximately 0C, a specific gravity of 1.18, anepoxy equivalent weight of from about 133 to about 154 and an averageapproximate molecular weight of from about 266 to 318.

[0032] A suitable phenoxy polyol resin is available under the trade name“PKHC”, or “PKHJ”, formerly from Union Carbide Corporation, now fromPhenoxy Resin Associates. A suitable octafunctional bisphenol A,formerly available under the trade name “Epirez SU8” from High TekPolymers, is now available as “Epon SU8” from Shell Chemical Company. Asuitable tetrabromobisphenol A formerly available under the trade name“Epirez 5183” from High Tek Polymers, is now available as “Epon 1183”from Shell Chemical Company. A suitable complex triarylsulfoniumhexafluoroantimonate salt photoinitiator, formerly available under thetrade name UVE 1014 from General Electric Company, is now available asUVI 6974 from Union Carbide Company. The UVI 6974 is a 50% solution oftriarylsulfonium hexafluoroantimonate salt in propylene carbonate.

[0033] The solids of the photoimageable dielectric film optionallycomprise a particulate rheology modifier, preferably a thixotropicparticulate rheology modifier. Preferably, the particulate rheologymodifier has an average particle size of from about 0.001 to about 10microns, more preferably from about 0.01 to about 5 microns. Examples ofparticulate rheology modifiers are barium sulfate, talc, aluminum oxide,antimony oxide, kaolin, finely divided silicon dioxide which may becolloidal or rendered hydrophobic, micronised talcum, micronised mica,kaolin, aluminum oxide, aluminum hydroxide, calcium silicate, aluminumsilicate, magnesium carbonate, calcium carbonate, zirconium silicate,porcelain powder, glass powder, antimony trioxide, titanium dioxide,barium titanate and barium sulfate or mixtures thereof.

[0034] Preferably, the particulate rheology modifier is silica; asuitable silica is available under the trade name Aerosil A380 silicafrom Degussa. Where the particulate rheology modifier is a thixotropicparticulate rheology modifier, it is preferred that no more than 30% beused.

[0035] Optionally, a surfactant, such as for example a nonionicsurfactant, is employed. Preferably the surfactant is a fluoronatedpolyether; a suitable surfactant is available under the trade nameFC-430, from 3M Company.

[0036] Any residual solvent content left over from the manufacturingprocess in the uncured photoimageable dielectric film preferably rangesfrom about 0 to 5%, more preferably from about 0 to 3%, most preferablyfrom about 0 to less than about 2%, by weight of the film.

[0037] While the invention had been described with a certain degree ofparticularity, various adaptations and modifications can be made withoutdeparting from the scope of the invention as defined in the appendedclaims.

What is claimed is:
 1. A laser ablatable resin consisting essentially ofan epoxy base, an effective amount of at least one dye that hassubstantial energy absorption at least one wave length selected from thegroup 532 nm, 355 nm, 308 nm, 266 nm, 248 nm, and 10,600 nm, and athermal curing agent.
 2. The composition as defined in claim 1 whereinsaid epoxy base consists essentially of between about 10% and about 80%by weight of a polyol resin which is a condensation product ofepichlorohydrin and bisphenol A; 0% to about 80% by weight of amultifunctional bisphenol A formaldehyde novalak resin; and 0% to about90% by weight of a glycidyl ether of bisphenol A.
 3. The composition ofclaim 1 wherein the curing agent is a thermally labile cationicphotoinitiator which can initiate polymerization of the epoxyfunctionality by exposure to light or by exposure to temperatures aboveabout 125° C. in the absence of light.
 4. The composition of claim 1wherein the curing agent is a thermally activated compound which caninitiate polymerization of the epoxy functionality by exposure totemperatures above about 80° C.
 5. The composition of claim 1 whereinthe dye is selected from the group consisting of rhodamine B, ethylviolet, 2′,7′-dichlorofluorescein, carbostyril 124, carbostyril 165,coumarin 2, coumarin 120, coumarin 4, p-terphenyl, and fluorescein. 6.The composition of claim 3 wherein the dye is selected from the groupconsisting of rhodamine B, ethyl violet, 2′,7′-dichlorofluorescein,carbostyril 124, carbostyril 165, coumarin 2, coumarin 120, coumarin 4,p-terphenyl, and fluorescein.
 7. The composition as defined in claim 1wherein said epoxy base consists essentially of between about 10% andabout 80% by weight of a polyol resin which is a condensation product ofepichlorohydrin and bisphenol A; about 0% to about 80% by weight of amultifunctional bisphenol A formaldehyde novalak resin; about 10% toabout 50% by weight of a glycidyl ether of bisphenol A; and about 10% toabout 35% of a liquid epoxy resin.
 8. The composition of claim 7 whereinthe curing agent is a thermally labile cationic photoinitiator which caninitiate polymerization of the epoxy functionality by exposure to lightor by exposure to temperatures above about 125° C. in the absence oflight.
 9. The composition of claim 7 wherein the dye is selected fromthe group consisting of rhodamine B, ethyl violet, 2′,7′-dichlorofluorescein, carbostyril 124, carbostyril 165, coumarin 2,coumarin 120, coumarin 4, p-terphenyl, and fluorescein.
 10. A processfor manufacturing an interconnect structure containing a buildupdielectric layer containing at least one opening comprising the stepsof: a) providing a substrate, b) coating the substrate with a dielectriccomposition for making interconnect films, said compositioncomprising; 1) an epoxy base resin, 2) from about 0.1 to about 15 partsby weight per 100 parts of a curing agent capable of initiatingpolymerization of said epoxy base resin; 3) from about 0.01 to about 1parts by weight of a dye having a substantial absorbtivity at thewavelength of emission of the light of a laser beam; c) curing the film;and d) forming at least one opening in the dielectric composition bylaser ablation.
 11. The invention as defined in claim 10 wherein theepoxy base resin has between about 10% and about 80% by weight of apolyol resin which is a condensation product of epichlorohydrin andbisphenol A; 0% to about 80% by weight of a multifunctional bisphenol Aformaldehyde novalak resin; and 0% to about 90% by weight of a glycidylether of bisphenol A.
 12. The invention of claim 10 wherein the curingagent is a thermally labile cationic photoinitiator which can initiatepolymerization of the epoxy functionality by exposure to light or byexposure to temperatures above about 125° C. in the absence of light.13. The invention of claim 10 wherein the curing agent is a thermallyactivated compound which can initiate polymerization of the epoxyfunctionality by exposure to temperatures above about 125° C.
 14. Theinvention of claim 10 wherein the dye is selected from the groupconsisting of rhodamine B, ethyl violet, 2′,7′-dichlorofluorescein,carbostyril 124, carbostyril 165, coumarin 2, coumarin 120, coumarin 4,p-terphenyl, and fluorescein.
 15. The invention of claim 10 wherein thedye is selected from the group consisting of rhodamine B, ethyl violet,2′,7′-dichlorofluorescein, carbostyril 124, carbostyril 165, coumarin 2,coumarin 120, coumarin 4, p-terphenyl, and fluorescein.
 16. Theinvention as defined in claim 10 wherein said epoxy base resin consistsessentially of between about 10% and about 80% by weight of a polyolresin which is a condensation product of epichlorohydrin and bisphenolA; about 0% to about 80% by weight of a multifunctional bisphenol Aformaldehyde novalak resin; about 10% to about 50% by weight of aglycidyl ether of bisphenol A; and about 10% to about 35% of a liquidepoxy resin.
 17. The invention of claim 16 wherein the curing agent is athermally labile cationic photoinitiator which can initiatepolymerization of the epoxy functionality by exposure to light or byexposure to temperatures above about 125° C. in the absence of light.18. The invention of claim 16 wherein the dye is selected from the groupconsisting of rhodamine B, ethyl violet, 2′,7′-dichlorofluorescein,carbostyril 124, carbostyril 165, coumarin 2, coumarin 120, coumarin 4,p-terphenyl, and fluorescein.
 19. A laser ablatable resin comprising anepoxy base, an effective amount of at least one dye that has substantialenergy absorption at least one wave length selected from the group 532nm, 355 nm, 308 nm, 266 nm, 248 nm, and 10,600 nm, and a thermal curingagent.
 20. The composition as defined in claim 19 wherein said epoxybase is comprised of between about 10% and about 80% by weight of apolyol resin which is a condensation product of epichlorohydrin andbisphenol A; 0% to about 80% by weight of a multifunctional bisphenol Aformaldehyde novalak resin; and 0% to about 90% by weight of a glycidylether of bisphenol A.
 21. The composition of claim 19 wherein the curingagent is a thermally labile cationic photoinitiator which can initiatepolymerization of the epoxy functionality by exposure to light or byexposure to temperatures above about 125° C. in the absence of light.22. The composition of claim 19 wherein the curing agent is a thermallyactivated compound which can initiate polymerization of the epoxyfunctionality by exposure to temperatures above about 80° C.
 23. Thecomposition of claim 19 wherein the dye is selected from the groupconsisting of rhodamine B, ethyl violet. 2′,7′-dichlorofluorescein,carbostyril 124, carbostyril 165, coumarin 2, coumarin 120, coumarin 4,p-terphenyl, and fluorescein.
 24. The composition of claim 21 whereinthe dye is selected from the group consisting of rhodamine B, ethylviolet. 2′,7′-dichlorofluorescein, carbostyril 124, carbostyril 165,coumarin 2, coumarin 120, coumarin 4, p-terphenyl, and fluorescein. 25.The composition as defined in claim 19 wherein said epoxy base iscomprised of between about 10% and about 80% by weight of a polyol resinwhich is a condensation product of epichlorohydrin and bisphenol A;about 0% to about 80% by weight of a multifunctional bisphenol Aformaldehyde novalak resin; about 10% to about 50% by weight of aglycidyl ether of bisphenol A; and about 10% to about 35% of a liquidepoxy resin.
 26. The composition of claim 25 wherein the curing agent isa thermally labile cationic photoinitiator which can initiatepolymerization of the epoxy functionality by exposure to light or byexposure to temperatures above about 125° C. in the absence of light.27. The composition of claim 25 wherein the dye is selected from thegroup consisting of rhodamine B, ethyl violet,2′,7′-dichlorofluorescein, carbostyril 124, carbostyril 165, coumarin 2,coumarin 120, coumarin 4, p-terphenyl, and fluorescein.